I am thinking of 3 ideas:
1) 52/17 min timer
From the concept of time blocking, an hour is changed to having 69 minutes. A button starts the 69-min hour, starting with the productive 52 min zone, and then the 17 min zone. The zone keeps looping. The change in the zone is based on the light colour. The brightness of the light indicates the beginning or end of a zone. The conical shape is divided into 69 segments.
There is also an option to have the user set the time productive time vs. break time needed.
2) Projection on ceiling or wall of sun and moon to bring the natural indicators of time inside a man-made environment
3) Shadow movement with colour change in an interior space portrait, or the sun and moon movement with color change in landscape painting in a portrait.
More Detailed Sketches of Idea 3 and 1 respectively:
I feel more inclined to do the lamp idea over the interior scene frame idea, mainly because of the challenges in fabrication. But I still do feel more excited to create the frame idea.